Electrical mystery-are you out there Poirot?

[Alanf1]

Cheers Mike, that's useful info.

I will check on the 230v charger as I'm not even sure it's a CBE but would have thought so as the rest of the setup is.

 

The other thing is the transit twin wheel chassis is a bit of an oddity with the starter and AUX batteries already installed and I don't want to fry the system for the sake of doing the research up front by adding an extra battery to the bank.

 

Good news of the Boite relais securitie, I'll not fiddle with it if it doesn't need it.

[aandncaravan]

First of all you need to establish how the existing batteries are wired.

On some vehicles the Ford Auxillary is the habitation battery on it's own.

On others it is paired with the Habitation battery and on some is not used at all in the habitation area.

 

Usually, where a second under Passenger seat battery is fitted it is paired with the Drivers seat Aux battery so adding two Habitation batteries to the 75Ah Aux battery might be a load too great for a system generally designed around a 150Ah Habitation battery bank. Later versions are a bit more powerful, but not much.

 

As an example of the limitations of the system, the Boite Relays are only designed to operate at a max 45amps, as demonstrated by the design and fitment of a 50amp fuse, so three habitation batteries could easily overwhelm them by drawing up to 60amps from the Alternator.

 

Such a draw of 60 + amps, would run from the Alternator, through the 'Split charge' Boite relay and then through the second Boite relay before reaching the habitation battery.

But remember we are not CBE specialists, so the actual route may be different.

 

 

Once you know how your existing set up is wired, we would suggest that you aim for a Habitation battery bank of no more than 180Ah if all the batteries are all the more efficient Powerframe.

Or 150Ah if they are less efficient conventional batteries.

 

Note that Gel batteries are slower charging because they draw less current when charging from an Alternator. If slow charging isn't an issue for you (they can literally take almost twice as long to charge as a Varta LFD) you could create a bigger Gel battery bank of about 200Ah?.

But remember Gel batteries are not ideal for drawing large or continuous current, like an Inverter draw.

 

 

The Ford OEM Silver Aux and Starter batteries are very expensive but the much cheaper, better, more powerful LFD75 fits a treat.

 

 

Whatever you do, may we suggest you don't fit Lithium batteries (of any technology - Cobalt, Manganese or Iron) because a 100Ah Lithium can draw 100amps from the Alternator, which you can see from the above is going to be an issue without major reworking.

 

 

Note : a 50amp fuse blows at 50amps, obviously the current it passes should be less than this, ideally with a few extra amps leeway, hence a 50amp fuse is normally used in a circuit pulling a continuous 40amps and 45amps peak. If each of your three batteries, in a heavily discharged state, drew 20amps, you can see there will be Tears.

If the batteries were also past their best, taking even more current than usual, then you can understand why some Boite Relays have an issue coping.

 

 

If the Aux battery is part of the habitation area then it obviously needs to be the same technology, age, size, etc. as the others.

 

 

 

[Alanf1]

Thanks Alan - that's really useful and food for thought.

In terms of how the habitation batteries are joined, I'm pretty sure the 2 batteries are linked via the output points on the back of the drivers seat, so the Ford AUX and hab battery are connected.

 

I initally considered AGM batteries as info suggests they are newer and better technology, however, having had a good read on your site it would appear they are not at all suited to MHs so I discounted them and the information you give on the Varta/Bosch batteries seems to suggest they are the correct tool for the job and a great battery to boot. So I think if I do go for replacements then these will be the choice.

 

Back to your post though and it would seem (as I probably suspected) that adding an additonal hab battery could well lead to problems with the relays and boards so perhaps this is not an ideal solution to the problem.

 

I guess one solution would be to replace the hab battery and the AUX battery with the Vartas and not add the additional battery. At the moment though the batteries that are present seem to be working fine so I'm loathed to swap them both while still doing their job.

 

I think I will give it a bit more thought before deciding how to proceed but it seems an additional leisure battery may give more problems than it's worth.

 

I suppose the other option would be to uncouple the AUX and hab batteries to make the hab battery bank smaller but then adding an extra battery is adding extra weight and doesn't seem to provide much in the way of extra capacity over what is already present.

 

Thanks again for answering my questions, much appreciated.

[aandncaravan]

We have come across some strange installations with the Ford Aux/Starter battery set-ups and only one had the batteries permanently joined together and we think that was a 'home grown' mod because it also had aftermarket 'not quite the right fit' batteries.

 

Derek knows the set up better than us, but in a Commercial White Transit van, the Aux battery is used to power the 'auxillary' lights in the rear of the van for Tradesman. For example extra LEDs in the back of a Carpenters van so he can work out of it all day without risk of the vehicle not Starting.

 

The Aux battery usually assists Starting but even this feature has been disabled on some Motorhomes we have worked on.

The Starter battery is very small, as little as 580 cranking amps (typically Ford OEM's are around 68Ah) on some vehicles, so using the similar size Aux to help at 'Start up' is a good idea.

When the Starter battery begins to fail, it often isn't noticed for a while as the Aux battery can mask it's true state.

Sometimes the Starter battery dies first, putting a strain on the Aux which fails before long.

Suggest that when you investigate, you check their condition? Because of it's small size, the Transit Starter battery tends to have half the life of a Fiat 90Ah in a typical Motorhome set-up.

 

 

In the Commercial White van it is an unusual set up, and can become even more so at the hands of some Motorhome manufacturers.

So suggest you do some investigation over the next month or two while you think.

 

 

Look for the chunky Ford relay that joins the Starter and Aux together when the ignition key is operated.

 

Then look for the wiring to the 'proper' Split Charge relay that joins the Passenger seat habitation battery to the Aux/Starter battery, sometimes located in the DS200, sometimes a Boite Securite relay setup on the DS300 (I think?).

Following this wiring will help you work out how it is set-up?

 

Remember to isolate the Solar Panel from the Regulator a few days before you start. Not just for safety but because the batteries will stabilise at their own individual voltages, helping to identify each one more easily than 3 all at the same charge 14.4v/13.4v charge voltage.

 

 

 

 

 

 

[Alanf1]

Fantastic - that's great I will check it all out and try and figure out how it is all linked up.

As you say it can be a bit hit and miss in how it's been adapted so getting to the bottom of that is the first part of the problem.

 

[Derek Uzzell]

aandncaravan - 2018-03-07 10:23 AM

 

Derek knows the set up better than us...

 

 

I’m reasonably familiar with a standard CBE-based system, but a Transit with Ford’s ‘twin battery’ arrangement plus Chausson’s use of “Boite Relais Securite” devices introduces extra unknowns.

 

Forum-member “Dr Dave” might be able to advise, as his Transit-based Chausson could well have a similar electrical system to Alan’s

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/CBE-PC200-control-panel/40668/

 

If the Ford-installed AUX battery is partnered to the habitation-battery that would have been added at the motorhome’s conversion stage, then replacing the existing single habitation-battery with a pair of new Varta LFD90 batteries would be risky. Even just replacing the existing single habitation-battery would mean there would be a new Varta battery connected to the ‘old’ Ford AUX battery unless the latter battery were also renewed.

 

Alan has said

 

"I guess one solution would be to replace the hab battery and the AUX battery with the Vartas and not add the additional battery. At the moment though the batteries that are present seem to be working fine so I'm loath to swap them both while still doing their job.”

 

That makes sense to me as, whatever the present electrical set-up is, it evidently works.

 

[Alanf1]

Thanks Derek, I'm going to check out how everything is connected first as at the moment I'm just going on memory so can't be 100% sure. Once I've established that then i may be able to come to some sort of conclusion as to how to proceed.

 

It does appear that adding an extra battery into the mix will do more harm than good.

[Alanf1]

I've managed to get the spec of units fitted in the van.

They are all CBE: P150 control panel, D300 fuse board and 516 charger.

 

I've checked the wiring from the AUX battery terminal on the back of the drivers seat and it is connected up, although what to I'm not sure as the cabling exits under the floor behind the seat. I'm assuming this is linked into the 12v system for the van and as such would be charged as per the rest of the 12v system.

 

I've not been able to get the seats off today to check the batteries but I'm working on the assumption that it's as per normal under the drivers seat and as I recall an 85AH battery under the passengers as the LB.

 

So working on the knowledge that the system currently is working as expected, what I don't want to do is push it outside of what would be possible by increasing the battery sizes.

 

So if I do go down the route of updating the batteries with Varta powergrid options should I go with similar sized options or can I take the LB up to a 90 and maybe the Aux as a 75 (would a 90 be pushing the system too hard?)?

 

Anyway that's one for the future to consider when I've got more time to check everything out fully

[Derek Uzzell]

Alanf1 - 2018-03-09 3:15 PM

 

...So if I do go down the route of updating the batteries with Varta powergrid options should I go with similar sized options or can I take the LB up to a 90 and maybe the Aux as a 75 (would a 90 be pushing the system too hard?)?

 

 

Replacing the present (85Ah?) habitation battery with a Varta LFD90 ‘Powerframe’ battery should present absolutely no problems (assuming that the present battery is wet-acid type, not gel or AGM).

 

Similarly, if a Varta LFD90 will directly replace the present ‘AUX’ battery (ie. there’s actually enough room in the seat-box for the Varta battery) thay should be alright too.

 

If you displace the seats and look inside the seat-boxes, you should be able to see if there might be any space problems.

[aandncaravan]

Ideally the batteries should be the same size, age, technology, etc. or one battery will tend to do more work than the other with resultant shorter life.

You may find that the imbalance of the existing set up of 68Ah Aux battery and 85Ah habitation battery means they might not be as good as you think?

Especially as the standard Ford OEM aux battery is Silver based to accommodate the higher 15v charging of the Commercial White vans ECU controlled Alternator. Although the ECU Alternators are usually disabled for Motorhomes, the high spec OEM batteries usually remain. These Silver technology batteries have quite different characteristics to the usual habitation battery.

 

So replacing the 85Ah habitation battery with a LFD90 in isolation won't be a good idea, because of the age difference and even greater imbalance.

 

Replacing both the 85Ah with a LFD90 and the 68Ah aux with a LFD75 (I don't think you will squeeze anything bigger under the Drivers seat) won't put any strain on the system, but I wouldn't expect optimum life.

 

 

If you replaced the single 85Ah Passenger seat battery with two LFD75's to match a similar new LFD75 Aux battery then the resulting 225Ah battery bank might be a bit much unless you manage the load in some way, like limit discharging down to a max of 12.4v.

 

 

 

 

[Derek Uzzell]

The attached photo shows the twin-battery arrangement in a Mk 7 Transit with two Ford-branded batteries in place.

[aandncaravan]

If the wiring follows that in the picture, disappearing behind the seat as also seems to be the description by the OP, then I would guess there is a pretty good chance the Aux and habitation are linked as I assumed above.

 

From other Transit Motorhomes we have seen, the wiring runs to the back of the seat, bottom of photo, where the Ford operated relay is sometimes found under the plastic cover.

 

It is from the junction points on the relay that the habitation wiring is often taken, but not sure if that applies to this manufacturer.

 

Simple testing will give you detailed info on the set-up.

If the Solar power is isolated the week before the test, each battery will reach it's own individual voltage.

 

Suggested Testing and verification of the set-up -

If the habitation earth battery clamp is removed, and a multimeter continues to show a voltage at the battery clamps, that voltage is most likely from the Aux battery.

Checking the voltage of the Aux battery should confirm it is the same voltage as that at the habitation clamp.

 

If the Aux battery clamp is then removed, there should be no voltage at the Aux clamps. If there is it will most likely be the Starter battery permanently wired

If the multimeter shows the Aux battery clamp voltage matches the Starter battery voltage then they are hard wired together, but that is unlikely.

 

 

If you then test the batteries while the clamps are disconnected, it should ensure you are only testing individual batteries, not coupled pairs.

 

See the bottom of the Battery Technology page for a section on how to test your own Habitation and Starter batteries.

Just above that section is another section on commercial battery testing : the different tools used and the limitations of those test devices for Motorhomes. See : http://www.aandncaravanservices.co.uk/battery-technology.php

 

Suggest you check the Ford OEM batteries for fluid loss. They are normally loss batteries, but a Solar Install can change that.

 

[Alanf1]

Thanks for the replies again - really useful info.

 

I didn't get a chance to get the seats off on Friday (both swivels so can't just slide forward and look) to check layout but I did check the relay on the back of the drivers seat and the cables are attached and then exit directly under the van floor from the relay output box.

 

I'll get the seats off and have a look and see what sized batteries will fit in the AUX space and also test to see what the situation is regarding the linking too.

 

Thanks again